diff --git a/src/common/utils.ts b/src/common/utils.ts
index d0a83fbf..470262f9 100644
--- a/src/common/utils.ts
+++ b/src/common/utils.ts
@@ -17,7 +17,7 @@ function dropsToXrp(drops: string | BigNumber): string {
   if (typeof drops === 'string') {
     if (!drops.match(/^-?[0-9]*\.?[0-9]*$/)) {
       throw new ValidationError(`dropsToXrp: invalid value '${drops}',` +
-        ` should be a number matching (^-?[0-9]*.?[0-9]*$).`)
+        ` should be a number matching (^-?[0-9]*\\.?[0-9]*$).`)
     } else if (drops === '.') {
       throw new ValidationError(`dropsToXrp: invalid value '${drops}',` +
         ` should be a BigNumber or string-encoded number.`)
@@ -51,7 +51,7 @@ function xrpToDrops(xrp: string | BigNumber): string {
   if (typeof xrp === 'string') {
     if (!xrp.match(/^-?[0-9]*\.?[0-9]*$/)) {
       throw new ValidationError(`xrpToDrops: invalid value '${xrp}',` +
-        ` should be a number matching (^-?[0-9]*.?[0-9]*$).`)
+        ` should be a number matching (^-?[0-9]*\\.?[0-9]*$).`)
     } else if (xrp === '.') {
       throw new ValidationError(`xrpToDrops: invalid value '${xrp}',` +
         ` should be a BigNumber or string-encoded number.`)